Technical Field
The present invention relates to a semiconductor device, and to a technique applicable to, for example, a semiconductor device provided with a first circuit and a second circuit having reference potentials different from each other.
Related Art
When a signal is transmitted and received between two circuits having reference voltages different from each other, photo-couplers are generally used. On the other hand, in recent years, there has been developed a technique in which a signal is transmitted and received between two circuits by inductively coupling or capacitively coupling two inductors (see Japanese Unexamined Patent Publication No. 2011-142175). The use of the technique allows the above-mentioned two circuits to be mounted to one semiconductor chip, for example, as disclosed in Japanese Unexamined Patent Publication No. 2009-295804.
The inventor has examined the formation of two circuits having a large difference between reference potentials using one silicon-on-insulator (SOI) substrate. In this case, noise coming into a circuit having a relatively large reference potential (hereinafter, referred to as a first circuit) becomes a very large value for a circuit having a relatively small reference potential (hereinafter, referred to as a second circuit). For this reason, even when a region in which the first circuit is formed and a region in which the second circuit is formed are insulated from each other in a semiconductor layer of the SOI substrate, it has turned out that noise is propagated from the first circuit to the second circuit through a semiconductor substrate serving as a base. Consequently, the inventor has examined the suppression of the propagation of the noise.
Other problems and novel features will be made clearer from the description and the accompanying drawings of the present specification.